In automatic transmissions, gearshifts are usually overlapping gearshifts, that is, a first clutch opens and a second clutch closes. Thus, U.S. Pat. No. 5,079,970, for example, proposes an overlapping gearshift for a downshift wherein, at the beginning of the shift, the pressure level applied to the first clutch is reduced to a lower pressure level according to a ramp function. This is followed by a time function during which the transmission input speed increases. The pressure curve of the second engaging clutch, consists of rapid filling, filling equalization and a load take-up phase. Downshifts are usually produced when an presettable accelerator pedal value exceeds a downshift characteristic line. Together with downshifts produced by means of the accelerator pedal, the driver also has the possibility of producing manual downshifts whenever desired. DE-OS 43 11 886, for example, shows a device by which with the aid of a selector lever the driver can produce gearshifts with a manual gate or shifting rocker on a steering wheel. For manually produced downshifts, for example, there arises, in practice, a problem of long reaction times, that is, the time interval, from the manual demanded downshift, until a noticeable reaction of the automatic transmission appears. Long reaction times result from the idle times of the signals controlling the hydraulic system, blocking times between two consecutive gearshifts and the time needed for the disengagement of the first clutch or filling of the second clutch. The long reaction times are felt as unpleasant by the driver.
The invention is based on the problem of improving the spontaneity of the automatic transmission, specially in a downshift and a double shift included therein.